100 
CENTRAL ILLINOIS 
B39 SOUTHERN ILLINOIS 
FREQUENCY (PER CENT OF COUNTS) 
/9 Os /9 /o /9 "5 /9 Be /9 Pe /9 35 /9 35 940 /9 45 /9 So 
Fig. 19.— Frequency of occurrence of the red-shouldered hawk in central and southern Illinois calculated for 5-year periods 
beginning in 1905 and ending in 1954. The year indicates the beginning of the 5-year period. 
25 
—O— CENTRAL ILLINOIS 
—4— SOUTHERN ILLINOIS 
NUMBER OF _ BIRDS 
/ / / / / / / /9 / / / 
Roger gen Sig eae eg ay ag IQ Me, 880 “OBS 
Fig. 20.— Average numbers of red-shouldered hawks reported per observer-hour in central and southern Illinois, 1903-1955. 
